This article presents the P-RIO environment, which offers high-level, but straightforward, concepts for parallel and distributed programming. A simple object-based software-construction methodology facilitates modularity and code reuse. This methodology promotes a clear separation of the individual sequential computation components from the interconnection structure used for their interaction. P-RIO provides immediate mapping of concepts associated with the software-construction methodology to their graphical representations. P-RIO offers a graphical programming tool, modular construction, high portability, and runtime support mechanisms for parallel programs, in architectures composed of heterogeneous computing nodes.